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By N. T. Moxon, D. Mead, S. B. Richardson

A laboratory and theoretical study of air decks was carried out to assess the effects of the size and location of air-decks on fragmentation. The degree of fragmentation was found to depend on both factors. As the size of the air-deck increases the degree of fragmentation is reduced relative to a full column charge. However, the reduction is relatively small until a critical size is exceeded. The critical size depends on the strength and structure of the surrounding material. A critical air-deck length of 30-35% of the original explosive column was determined for the model materials used in the study. A theoretical explanation of the results was derived based on pressure decay rate relationships. The location of the air-deck also influences fragmentation. The interaction and oscillation of the two shock fronts from the top and bottom charges mean that mid-column air-decks produce better fragmentation for the same air-deck length and explosive loading as top-column or bottom-column air-decks.

Jan 4, 1993

Discussions of the papers with a written contribution on Paper No. 11 and authors' written replies. Also brief obituary of Dr. T. David Jones on p146.

Jan 1, 1947

By R. J. Pine

Procedures are described for the application of risk analysis or probabilistic methods to mining geomechanics. The methods are widely applicable to existing mine design models. Detailed examples are given of plane slope failure and of pillar design based on displacement-discontinuity stress modelling and empirical strength assessment. The modelling techniques assessed are the Latin hypercube sampling method, incorporated in a spreadsheet environment, and the general point estimate method (GPEM), programmed in TurboBasic. An example GPEM program listing is included. Both methods are very convenient to use. Probabilistic acceptance criteria for slope stability after Priest and Brown are examined and alternatives are proposed where output distributions of factor of safety are approximately normal or lognormal and output distributions of safety margin are normal. The reliability index is included as a useful measure of variability with proposed acceptance criteria.

Jan 12, 1992

By C. C. Harris

The two best known graphical methods for presenting and comparing comminution data are obtained by linearising the Gates-Gaudin-Schuhmann and the Rosin-Rammler size distribution equations. It is shown that the Gates-Gaudin-Schuhmann equation can cause excessive congestion in the 50 per cent oversize range and that, overall, the Rosin-Rammler is a better procedure. Examples are given

Dec 1, 1971

By R. F. Bell, Schultz

The paper briefly discusses the nature of spontaneous heating in mines in the Doncaster area, in the period immediately before 1967 and steps taken to prevent and treat such outbreaks. The changes that led to the increased rates of advice of Barnsley Seam faces since 1967 are listed and the effects of these increased rates on the frequency and location of spontaneous combustion are discussed. The change in methods of control required by the increased rate of advance of the faces and the changes in location of outbreaks are described. Some typical heating situations are evaluated. The methods described include the use of air sealants, water gels for filling of voids in wastes, the balancing of pressures across heating areas by pressure chambers, booster fans, and the resiting of air separation doors, and the sealing of air-ways by flooding. The authors discuss the influence of mine layouts on the risks of spontaneous combustion and advocate that future plans should be designed to limit the number of districts at risk when heatings occur.

May 23, 1905

By D. G. Skinner, M. SC. Griffiths

"The natural difficulties associated with the size evaluation of dusts render absolute measurement difficult, or indeed, impossible. Assuming that the desirability of gravi­ metric sampling be conceded, it appears likely tha,t the most suitable means available for physical evaluation are the method of total turbidity measurement, to give a con­ ventional value for specific surface, together with microscopical examination, the great merit of the latter being that in the hands of an experienced operator, semi-quantitative discrimination between coal and other particles is possible.The pipette method, as modified by Fryer, probably-deserves more attention than it has received up to the present. Whatever method is used, it is recommended that in view of the lack of medical knowledge, as much information as possible should be obtained with reference to the total mass concentration, the surface area of the total dust,' and the mass and area of the particles below 5μ in size."

Jan 1, 1947

By Emanuel Shinwell, Douglas Hay

"Opening statements relating to the health and welfare of underground workers and the nature and prevention of silicosis and pneumokoniosis. During 1945-47, 10,500 UK coal-miners were certified by the Silicosis Medical Board to be suffering from pneumokoniosis and suspended from work in the industry. Over 80% of cases occurred in the South Wales coalfields. Silicosis and pneumokoniosis also occur among metalliferous miners, such as the tin-miners of Cornwall. The slate-quarries of North Wales are also troubled by these conditions as are the haematite mines of the North-West of England."

Jan 1, 1947

By Simons W.

The object of the paper is to describe the standards of quality that should be specified in ordering material ordinarily required for colliery use, and also the qualities most suitable for particular purposes. Tables are presented of British Standard tests for wrought iron grades A, B and C, Admiralty tests for iron in chain, the quality of material for wheels and axles, and the composition and mechanical properties of wrought iron, Armco (ingot) iron and drawbar-gear steel. (Paper presented at the North Staffordshire Institute of Mining and Mechanical Engineers' general meeting held in Stoke-on-Trent, March 27th 1916, Mr. John Gregory, President, in the chair)

Dec 1, 1916

By E. H. Baker

Vapour pressures of sulphur have been measured over the temperature range 340-1039°C by means of boiling-point measurements, an internally heated pressure vessel being employed with argon as the pressure medium. The results are expressed satisfactorily by a four-term pressure-temperature relation. At the cited critical temperature of 1040°C the calculated critical pressure is 204 atm. From the pressure-temperature relation and available thermal data for the vapour, the approximate composition of the saturated vapour in terms of the various molecular species has been derived for the critical point

Dec 1, 1971

By Groom P.

Discussion of the paper presented at the Midland Institute of Mining, Civil, and Mechanical Engineers' general meeting held in Leeds, March 21st, 1916, with T. Beach, vice-president, in the chair included contributions by Beach T., Fearnsides W.G., Lloyd W.D., Gill J. and Nadin R.

Dec 1, 1916

By R. W. Ruddle

The present state of knowledge on this subject may briefly be summarized as follows: (1) The copper content of the slag increases with the grade of the matte in contact with it; on the other hand, the proportion of copper lost decreases as the matte grade increases, because as a general rule a smaller volume of slag is produced when a high-grade matte is made. (2) The presence of CaO and MgO in the slag decreases the copper content of the slag, and the presence of ZnO increases it; the presence of A1203 seems to have little effect. The influence of the silicate degree is not yet clarified, but on theoretical grounds it seems likely that the copper content increases with the silicate degree of the slag. (3) High slag viscosity, high magnetite contents and low density difference between matte and slag all tend to increase the copper loss. The volume of slag is also an important factor. (4) The effect of bath temperature on the copper loss is not clear and further investigation of this point is needed. (5) It appears possible to recover a large part of the copper in the slag by adding FeS, CaS and other sulphides

Jan 1, 1953

By M. Rahman, P. C. Kapur

The fixed-time locked-cycle grinding test is employed to simulate the industrial closed grinding circuit on the laboratory scale. A mathematical algorithm for 'cyclewise' computer simulation of the locked-cycle test has been derived and used to study an idealised laboratory-scale model of a closed ball-mill circuit. The agreement between simulated and experimental results is reasonably good, except when the grinding times are relatively long

Dec 1, 1971

By Haldane J. S.

(Paper presented at the Institution of Mining Engineers' general meeting held in London on 8th June 1916.) It was shown in the last Supplement to the Registrar-General's Reports, in connection with the census of 1901, that the general death-rate among colliers was considerably lower than in the great majority of occupations but that there is an exception to this in the case of colliers above the age of 55. Examination of the statistics finds that the excessive death-rate among old colliers is to a large extent only apparent, and that the real excess of bronchitis from which they have suffered has greatly diminished. It is concluded: (1) that good ventilation is of considerable importance to the health and continued working efficiency of miners, as well as to their safety from accidents; and (2) that there is no real statistical evidence of harm resulting from the inhalation of coal-dust or shale-dust in the quantities ordinarily breathed by miners, and a strong presumption that the dust they breathe protects them against serious dangers from bacilli that are removed from the lungs by the dust-clearing cell mechanisms

Dec 1, 1916

By R. J. Bridges

Mining operations on the Witwatersrand are conducted for the most part in rocks of highly quartzitic character. They comprise the following types: Conglomerates, grits, and quartzites, to which on the Far East Rand must be added fine-grained quartzitic shales and shales. In addition, vein quartz occurring as small veins, veinlets and fissure fillings, and igneous rocks forming dykes, must be mentioned, although they constitute only a small percentage of the rock broken. The following is an account of the character and mineralogical composition of the various types.

Jan 1, 1947

By C. T. Shaw

Fur a secure mineral supply position to be maintained in the Fiuropean Community there must be a supply of qualified people in the minerals industries. The education of the people required to run and develop these industries should be a priority in the community. This means that there should be a strong capability in mining engineering education. The mining engineering professors decided in 1990 to get together in a new Society to discuss the problems. The Society of Mining Professors/Societat der Berg-baukunde was formed at a meeting in Austria in October 1990. It is basically a F.uropean Society with a few member professors from outside Europe to keep the Society conversant with trends elsewhere. The objectives of the Society are to see that the mining universities in Fiurope maintain standards and produce enough mining engineers. The present membership of the Society and the work of developing a database of current courses is described. Working from the knowledge base developed, it will be possible to design a 'European' mining degree course. The problems which will have to be addressed have been identified and are described in detail.The paper finally goes on to discuss the other problems that universities are facing, the economic problems and above all the lack of students applying for mining courses across Europe. The help and active participation of the mining industry, if that industry still wishes to employ mining engineers, is identified as the only possible solution to those problems.

Jan 1, 1993

By A Misra

In pursuit of solving the development rate problem the coal industry has investigated various development systems. While all the systems may improve the development rate they may not necessarily he cost effective. This paper carries out an economic analysis by developing cost models for present and future development systems for retreating longwall faces with particular reference to Australian longwalls. A critical cost analysis of various development systems is presented by taking into consideration all the costs associated with development systems. The costs have been divided into equipment, face and panel services, belt and structure, wages, roof and rib support, ventilation, consumables, power and maintenance. The annualised cost of various equipment has been obtained on the basis of depreciation rates prescribed by the Australian Taxation Office.

Jan 11, 1996

By R. Immele-Meziou, G. J. Long, D. G. C. Robertson, O. A. Pringle

The reduction of naturally weathered ilmenite concentrate occurs in two steps: reduction of Fe3+ to Fe2+, followed by reduction of Fe2+ to Fe. Small amounts of a magnetic phase were also observed and may correspond either to an Fe3O4-FeTiO3 ilmenite phase or to an Fe3O4-Fe2TiO4 spinel phase. The total amount of metallic iron produced after 12 hr was only 50% of the total iron present in the sample.

Jan 4, 1992

By G. H. Blackwell

Sequences in open pit mining must be planned and regularly revised to incorporate changes in the variables which affect profitability. Interactive computer planning with colour graphic facilities is an effective tool for this purpose in the short and medium term. An interactive computer planning system for medium-size, low grade porphyry copper-molybdenum open pits is described. The planning system proved especially valuable during the critical stages of pushback mining when deep, inner pit ore was nearly depleted and the erratic grades of the next pushback provided ore and marginal material at a time of depressed metal prices.

Jan 8, 1993

By Groom P.

The wastage of timber in coal-mines that is caused by decay is very great; in fact, far greater in this country than is generally realized. Mr. E. W. Peters estimates that of the whole wastage of timber in mines in the United States of America, 50 per cent, is due to decay and insects; of this 50 per cent, an overwhelming part is due to decay. The most efficient methods of decreasing this grave loss can be devised only by co-operation of the mining engineer and the scientific expert, and it is partly in the hope of procuring such collaboration that this paper is written. It contains, therefore, a resume of our present knowledge of the decay of wood, and of the economic methods of checking this in mines; but, with a view to improving those methods, it also directs attention to the gaps in our knowledge and the means by which these can be filled by future investigation

Dec 1, 1916

By J. V. Wood, P. Davies, J. L. F. Kellie

A new range of wear-resistant materials is being produced by technology that has been used to develop high performance metal-matrix composites. These include steels and aluminium alloys that can be made as sheet, plate, rod or bar. The incorporation of hard, wear-resistant particles in an alloy matrix is achieved by reactive casting, spray deposition and powder metallurgical techniques. For example, large particles of TiC can be homogeneously distributed in steel during casting and the subsequent product can easily be rolled to plate. Similarly, up to 20% alumina particles and SiC can be injected, respectively, into steel and wear-resistant aluminium alloys by spray deposition. The current state of development of the process is reviewed and indications are given of the projected applications of such materials.

Jan 12, 1992